There are driving ranges for practicing golf, in which golf balls are hit facing water surface of a lake and collected from water. The golf balls should float on the water surface and therefore have a specific gravity of less than 1.0. These types of driving ranges are called hereinafter as “water-facing driving range” and these golf balls are called as “floatable golf ball”. The performance, which is required for golf balls for usual land-facing driving ranges, is firstly excellent durability, and secondly good shot feel as good as golf balls for round games.
In case of the floatable golf balls for water-facing driving ranges, since it is further required to float on water in order to easily collect the golf balls after hitting, it is a necessary condition for the golf balls to have a specific gravity of less than 1.0. As a golf ball which satisfies the required performance, that is, durability, shot feel and specific gravity, one-piece golf ball has been mainly employed. This is because the one-piece golf ball is suitable for satisfying the required performance, and particularly because the golf ball has excellent durability.
Recently, it has been required also for the golf balls for usual driving ranges to have excellent performance nearly as good as golf balls for round games. Therefore so-called two-piece golf ball, which is formed by covering a cover, has been employed as a floatable golf ball for water-facing driving ranges. A two-piece floatable golf ball for water-facing driving ranges, which has low specific gravity and floats on water, and has good shot feel nearly as good as golf balls for round games, is proposed (Japanese Patent Kokai Publication No. 327791/1994 and the like).
However, the golf ball for round games has possessed very soft and good shot feel and high rebound characteristics by the recent remarkable improvement of performance of the golf ball. Therefore the two-piece floatable golf ball for water-facing driving ranges was evaluated to have good shot feel when it was proposed, but such a conventional golf ball for driving ranges does not agree with requirement for the existing golf ball. It is problem that the conventional golf ball for driving ranges is very hard and has poor shot feel, because the core is hard and stiffness of the cover is too high.